How do we use Gnangara groundwater?
The Gnangara groundwater system is Perth’s lowest cost and largest source of good quality water. The Gnangara groundwater areas consist of three main aquifers – the unconfined Superficial aquifer (commonly known as the Gnangara Mound), the deep, partly confined Leederville aquifer and the deep, mostly confined Yarragadee aquifer.
The Gnangara system currently provides almost half of all the water used in the Perth metropolitan area each year. It supplies water for agriculture, parks, ovals and gardens on the Gnangara system, and water for Perth’s scheme supply – distributed by the Water Corporation.
Gnangara groundwater also supports environmental features such as lakes, wetlands and bushland areas.
Gnangara groundwater is Perth’s lowest cost water source and the economic benefits have been estimated at a total net present value of $6.7 billion, which is equivalent to about $400 million a year.
Perth's scheme water
Gnangara groundwater currently provides 111 billion litres or 111 gigalitres (GL) a year for Perth’s scheme water supplied by the Water Corporation (enough water to meet the needs of over 800,000 people).
Horticulturalists and farmers take more than 60 GL of groundwater a year to irrigate locally grown vegetables and fruit.
Parks, gardens and reserves
Local councils, schools and sporting clubs take about 45 GL a year to irrigate parks, sports ovals and other public open spaces.
Other licensed use including commercial purposes
Local businesses, commercial industries, mining, and licensed stock and domestic users take about 21 GL a year.
Domestic garden bores
We estimate 70,000 individual households in the Gnangara groundwater plan area take about 36 GL a year through domestic bores to irrigate gardens and livestock (exempt from water licensing). See the Be Groundwater Wise website for more information on how we manage domestic garden bores.
Pine plantations intercept rainfall and reduce or prevent recharge to groundwater.
How much water is used from the Gnangara groundwater system?
Gnangara groundwater supports households, businesses, parks and gardens, through about 2600 water licences to take groundwater and 70,000 domestic bores.
In 2019–20, about 275 GL was allocated from the Gnangara system – enough water to fill Optus Stadium 275 times or 110,000 Olympic swimming pools.
Over 40 per cent of this went into the Water Corporation’s Integrated Water Supply Scheme, and about 46 per cent was used for local parks and grounds, horticulture, and businesses.
About 14 per cent was taken for gardens by households using domestic bores.